Control of electric motors and apparatus therefor.



APPLICATION F ILED NOV. 12, 1913.

Patented Sept. 1, 1914.

5 SHEETSSHEET 1.

INVENTOFIS P. N. JONES & J.., W. WELSH.

CONTROL OF ELECTRIC MOTORS AND APPARATUS THEREFOR.

APPLICATION FILED NOV. 12, 1913.

Patented Sept. 1, 1914.

'5 SHEETS-SHEET 2.

P. N. JONES & J. W. WELSH. CONTROL OF ELECTRIC MOTORS AND APPARATUS THEREFOR.

APPLIOATION FILED HOV. 12,1913.

Patented Sept. 1,1914.

5- SHEETS-SHEET 3.

Imam-0R5 WITNESSES all. 4;... I f. M

P. N. JONES & J. W..WELSH. CONTROL 0'? ELECTRIC MOTORS AND APPARATUS THEREFOR.

APPLICATION FILED NOV. 12.1913.

Patented Sept. 1, 1914.

5 SHEETS-SHEET 4.

mvzni-rons WITNESSES ddkw $721544 ma kwme.

max

APPLICATION FILED NOV. 12,1913.

Patented Sept. 1,1914.

5 SHEETS-SHEET 5',

Ma/ZciZ/Mg/ PEARL N. JONES AND JAMES 'VV. VJELS H, F PITTSBURGH, EENNSYLVANIA.

CONTROL OF ELECTRIC MOTORS AND APPARATUS THEREFOR.

Specification of Letters Patent. I

Patented SJQPt- 1, 1911 i.

' Application filed November 12, 1913. Serial No. 800,502.

To all whom it may concern:

Be it known that we, PnAni. N. Jones and Janus \V. \VnLsi-r, both residents of Pittsburgh, county of Allegheny, and State of I Pennsylvania, have invented a new and use-- ful Improvement in the Control of Electric Motors and Apparatus Therefor, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming part of this specification, in which Figure 1 is a wiring diagram of the power circuits as arranged for carrying out one form of our improved method of control; Fig; 2' is a development of the master controller which may be employed for controlling the operation of the contactors of Fi 1; Fig. 3 is a diagram illustrating the motor connections and relations in different posi-,

tions of the master controller; Fig. '4 1s a View similar to Fig.1, but illustrating a modification; Fig. 5 is'a view similar to Fig. 2, but showing a. master controller for use in connection with the control method illustrated by Fig. 4; Fig. 6 is a view, similar to Fig. 1, but showing another modification; Fig. 7 is a wiring diagram of the master controller and controlcircuits employed in connection with the arrangement shown in Fig. 6; Fig. 8 is awiring diagram showing another modification, and showing the rela tion between the power and'control circuits; Fig. 9 is a view similar to Fig. 1, but showing another modification; Fig. 10 is a view similar to Fig. 2 and showing a .zraster con-. troller adapted for use in connection with the circuit arrangement of Fif 9; Fig. ll

is aview similar to Fig. 3, but showing the motor connections and relations which result from the arrangements oi Figs. 9 and 10; Fig. 12 is a wiring diagram showing a form of our invention in which, instead of a master controller and a plu ality ct contactoi's controlled thereby, the motors are connected directly to and controlled by the contacts of a drum controller; and.Fig. 18 is a detail view of the circuit opening switch shown in F i g. 12.

Our invention has relation to the control of serieswvound electric motors, and more particularly for use in connection with the driving nictors of electrically propelled vehicles. The invention is more particularly adapted to the control of four electric motors, although some of its features are not specifically limited to such use.

b'omc of the more important objects of our invention are as follows:

First. To provide an improved method for changing the motors from series-parallel position to full-parallel position. ()ur invention provides a series of steps whereby this change an be eilected in a gradual and;

easy manner, no less than three of the motors being actively in circuit at all times during this change.

Second. To provide a method of changing the motors from series position to full-parallel position by a series of gradual and easy transitions in which no less than three motors are actively in circuit at all times.

Third. To effect the change from series, or fromseriesparallel position, to full-par; allel position with the use of a minimum amount of external resistance. Our method provides means whereby very little external resistance is required and whereby ineach case a resistance may be employed which is suitable for the particular condition then existing.

Fourth. To provide means of novel and effective character for reducing the arcing at the switch contacts.

Fifth. To'provide for an interlocking action between some of the contactors whereby establishing of short circuit between the trolley and ground is prevented, and whereby the fourth object above stated may be accomplished.

Sixth. To provide a control system or method in which either pair of motors may be cut out of circuit either wholly 'ithout opening the power circuits. or by opening said circuits to a minimum extent.

Seventh. To provide apparatus of simple and effective character for carrying out the previously stated objects.

The nature of our invention will be best understood by reference to the accompanying drawings in which. we have shox number of different modifications the: and which will now be described, it being premised, however, that the invention is susceptible of various other modifications within the scope of the appended claims.

Referring first to that form of our inven tion illustrated in Fi s. 1, 2 and 8, the nur, merals 1, '2, 3 and s designate four elect 'ic motors. A, r5, G, D, E, F and G designate the contactors or switch devices by means of which the power circuits of the motors are controlled. The mo *able elements of these contactors may be actuated in any suitable manner. In the forms of our invention illustrated herein, they are actuated by means ol solenoid coils whose circuits are controlled by master controller. R designates another contactor which is for the purpose of controlling the external resistance Re. Gr indicates a ground connection.

The different positions of the master controller l IO are indicated by the dotted vertical lines in Fig. 2, and the corresponding motor connections and relations are indicated diagrammatically in Fig. 3. For convenience, the relatively fixed contacts of the master controller are given lower case reference letters which correspond to the various contactors which they control. In this manner the open or closed position of each contactor in any position of the master conller can be readily seen by a comparison .1 and 2.

In the first position of the master con trollcr, contactors A and G are closed, the other contactors being open. The four motors are therefore connected in series with .ZlCll other and with the resistance Be in the manner illustrated in the first position of Fig. 8. At the second position of the master controller, the only change is the closing of contactor R to thereby short circuit the resistance Ile. In the third position, contactors B, A and F are closed and the contactor G is opened. The closing of contactor F and the opening of contactor G cuts the number 3 and number 4- moto'rs out of circuit am. leaves motors numbers land 2 in series with each other. In the fourth position of the master controller. contactors R, F are closed. This connects the our mot. in two series-parallel connected groups or pairs, the direction of current flow through the motors 3 and 4: being reversed. with respect to the direction of flow thcrcthrouglr in positions 1 and 2 of the master controller. The next position of the master controller (marked 25?) is a transition position. In this position, contactor-s l) and F are closed. This short circuits motor number I and places number 2 in series with the resistance Ile and said motor and resistance in series-parallel with the two motors 3 andl.

In the lith running position, contactor-s It, D, I), In and F are closed. In this position the motors 3 and 4: are connected in series with each other and the motors l and 2 are each connected across the line and in parallel with motors 3 and t, which latter two are still in series. the sisth run 1g position the only T indicates the trolley connection and change which has occurred from position five is the closing of contactor C and the opening of contactor D. This short circuits motor number t and leaves motors numbers 1, 2 and 3 in parallel.

In the seventh running position the only change which occurs is the closing of contactor G thereby connecting motor number 4 in parallel with motors 1, 2 and 3.

It will be seen that in passing from the series-parallel condition of position number t to the full-parallel relation of position 7, three of the motors are at all times actively connected in'circuit. In making this transition the only external resistance employed is that temporarily inserted in series with motor 2 at the transition position. This resistance is immediately cut out and motors 1 and 2 are each given full line voltage. Motors 3 and l are successively placed in parallel. It will further be noted that from the initial series position to the full-- parallel position there has been maintained a constant series connection between the motors. This feature, however, while-presenting certain advantages, is not essential to our present invention.

The modification illustrated by Figs. 4 and 5 effects thesame motor combination and series of steps as illustrated by the preceding figures. The difference between the two forms consists solely in the apparatus employed. In the form shown in Figs. 4 and 5 the circuit connections are so arranged that the contactor E is omitted. This is made possible by connecting one of the contact points of the contactor D with the circuit wire leading to motor number 1 between said motor and the contactor A. This, of'course, requires slight modifications in the master controller MG. It will, however, be unnecessary to describe these in detail as they are clearly apparent from the diagram itself. In order to avoid confusion, the corresponding parts have been given the same reference characters as in Figs. 1, 2 and 3.

Fig. 6 shows the power circuits and Fig. 7 the control circuits of another form of our invention. Fig. 6 is similar to Fig. 1 in the general arrangement of circuits and contactors; but in this form we employ two external resistance coils Re and Re and provide an additional contactor It for this resiStiUlCG. The resistance Re controlled by the contactor It is shown as placed in. series between the trolley and the power circuits; while the resistance It is arranged to be connected into the power circuit between motors numbers 1 and 2. In order to avoid confusion we have again employed the same reference characters in Figs. 6 and 7 as in the preceding figures, to designate corresponding parts. The construction and arrangement shown 111 these figures efiects the tain of the motor connections during the return movement of the master controller. By maintaining these connections during such return movement. the motors are held in closed local circuit which provides a closed path for the discharge of the electric energy of the motors and thus relieves the jaws of the contactor switches from breaking heavy arcs. This feature also decreases the number of operations of the switches onthe return stroke.

The closed local circuit around the motors,

it is true, contains the counter-electromotive forces of two motors which are opposing each other, but since in practice these are. never exactly equal, one lmmediately overpowers the other, reversing itspolarity and thus allowing the stored electrical energy of the motors to be rapidly dissipated within the local circuit.

The object of the holding, in interlocks on the contactors is to maintain whatever-arrangement of circuits exists at the instant of starting to throw the controller off until the oil' position is reached, without establishing any new, circuits. In other words, whatever contactors are closed on any given notch from which the controller is thrown oil, are held closed until the of? position is reached.

ny reference to Fig. 6, it-will be apparent that if the contactors D and G should, by any possibility be closed at the same time,

a direct shortcircuit would be established are. .1 the motors betwee trolley and groan 1. Such ashort circuit would also be established it the COIititCllOIS a and E should be closed at the same time. lVe therefore provide interlocking means whereby only one of the two switches of each of these sets can be closed at the same time. These interloclzs are controlled by contacts operated by the co-ntactors of certain of the power circuit switches. The coil or winding of each of the solenoids which operate the contactors are connected at one side to ground, as shown in Fig. 7. Their other terminalsare connected either directly or indirectly, to those relatively-fixed contacts of the master controller'MC which are given lower case letters corres xmdingto thenp per case let tors designating the respective contactbrs. The circuit connection leading from the eontact a to theisolenoicl of contactor A is of the contactor E.

tact 2; of the contactor G.

' contact 29.

connected to said coil through the fixed contacts 10 and 11 and movable contact 12 The contact 12 is connected to the movable member or armature of the contactor E; and this contact closes the circuit between the contacts 10 and 11 only when the solenoid of the contactor E is decii'ergized. Therefore the circuit of the coil of cont actor A cannot be closed as long as contactor E is closed. In a similar manner-,the conductor leading from contact 6 of the master controller is carried through the contacts 13, 1st and 15 ot' the cont-actor A, contact 14: closing the circuit between the contacts 13 and 15 only when contactor A Therefore contactor E cannot be is open. energized and operated so long as contactor A is energized and closed. In a similar manner the conductor leading from contact (Z of the master controller to the coil of contactor D is carried through the contacts 16,

17 and 18 of contactor (Pr; and the circuit of said coil cannot be closed when contactor G is energized and closed. The conductor leading from contact'or g of the master controller to the solenoid winding of contactor G is connected in a similar manner through the contacts 19, 20 and 21 of contactor .1), whereby contactor. G cannot be energized and closed so long as contactor D is energized and closed.

The holding closed of certain of the contactors during the return stroke of the master controller is accomplished as follows: The conductor-leading from the contact f of the master controller has a branch 22 which is connected to two contacts 23 and 2- of the contactor E. Opposite the contact is a contact 26 which is connected to the coil of centactor E. vVhen contactor E is closed its contact 12 bridges the two contacts 2 and 26, thus maintaining the coil of contactor Eenergized so long as contact fingers f-or g are in engagement with their corresponding contacts on the drum of the 1P tcr ccntr Opposite the contact 24: t a contact 2; which is connected to a con- Contacts 24 and 2? are bl'lt d by contact 29 of the contactor E when said contactor is energized. ()pposite the Contact of contactor G is another The two contacts 28 and 29 are ar 'anged to be bridged by the contact 17 of the contactor G when the coil of the latteris energized. Contact 29 is connected to the coil of contactor G. 'llhcreforo when this coil has been energized it is-kept enorgized on the retnrn strclce so long as the contact lingers or y maintain their engagement with the corresponding contacts on the controller drum. The contactor D has two contacts 30 and 31 which are arranged to be bridged by the contact 20 when contactor D is closed. Contact 31 is connected to the coil of contactor D and contact 30 is connected to a contact 32 of the contactor B. Opposite the contact 32 is a contact 33 which is connected with the conductor lead ing from controller finger a. Contacts 32 and 33 are arranged to be bridged by a movable contact 3% actuated by contactor B, and only when contactor B is open.

3y reference to Fig. 6, it will be seen that when the contactors E and G close the motors are connected in two. closed local circuits, the connection through the contactor F acting as an equalizer. Therefore, by holding these contactors closed during the return stroke of the master controller to its off position the opening of contactors B, C. and R and R is effected while the motors are connected in these closed circuits. This protects the contactor jaws against the se vere arcing usually caused by the backkick from the motors when the switches are opened. By our improved method the energy of the motors is dissipated in these clOSCtl circuits. The contactors 30, 31, 32, 33 and 34 and their connections have a twofold purpose. As just described, contactor G will be held closed clear to the off position of the controller during the return stroke, since as soon as contact finger f leaves its segment on the drum of the controller, contact finger 9 again engages its segment. The circuit for energizing contactor D comes through the back contacts of the contactor G;-and normally the coil of contactor D can only beenergized when contactor G is open. By the provision of contacts 30, 31, 32, and 34, we provide means for energizing the coil of contactor D from the a finger of the master controller. These contacts provide means for holding contactor D closed to the off position in the event that the forward movement of the master controller has not been carried beyond the fourth, or series-parallel position. This provides a closed local circuit around the motors through contactors-A and D. By the provision of the interlocks above described we therefore not only greatly reduce the arcing at. the contactor jaws, but we also eliminate, very largely, the tendency of arcs beingformed between certain of the master controller contacts.

Fig. 7 also illustrates another feature of our invention referred to in the statement of objects, but not heretofore described. This is the arrangement of the cut-out switches for the motors in the control cir cuits in such a manner thateither pair of motors may be cut out of circuit wholly by chan es in thecontrol circuits and without opening the power circuits at any point. This not only avoids the necessity for open ing certain of the power circuits in cutting out either pair of motors, but it avoids the necessity for bringing any of the power circuit wires above the floor of the car. We

accomplish this result by the arrangement of thecut-out switches now to be described: CO designates the cut-out switch for motors l and 2, and U0 the cut-out switch for motors 3 and i. These cut-out switches are shown as of themanual double-throw type. Switch CO has three blades 35, 3c and 37. The blade 35 forms a part of the connection between the contact finger (t and the coil of contaetor A. The blade 36 forms a part of the connection between the contact finger 7) and the coil of contactor B. The blade 37 forms a part of the connection between the contact finger r and the coil of contactor R. Fig. 7 shows the switches in the normal running positions. Switch CU has only one fixed contact 38 which it engages in its cut-out position. This contact 38 is connected with the conductor leading from the r finger to the coil of the I contactor. hen the switch CO is thrown to its cutout position, the circuits of the coils of contactors A and B are opened and the normal circuit of the coil of contactor It is opened, but this coil is connected in circuit through the contact 38- with the r finger. The purpose of this will he a 'iparcnt by reference to the development of the master controller drum. If the coil contattor ll were left connected to the r finger, the coil cont-actor It would be energized on the forward movement of the master controller between the first and second positions. and this resistance would be short circuited before a running position of motors l and 2 was reached. By the arrangement just described. resistance Re kept in circuit until a short time before the fifth position is reached.

-The sequence of operations with the cutout switch thrown to its cutting out position is as follows: In the first position of the master controller the contactor G is closed, but as the contactors D and F are still open there is no circuit. This'is like wise the condition in the second position.

At the third position contact finger f engages its corresponding segment on the drum and contactor F is closed and contactor G is opened. At the fourth position contactor D is energized, and the two motors are connected in series with the. resistance Re. This condition remains until the fifth position of the controller, when the resistance Re is short cii'cuited by the closing of a contactor It. In this position also contacttn' E is energized but no circuit change is effected. At the sixth position contactor C closed, thus short circuiting motor number 4. At the seventh position cont-actor Gr is closed and contactor D is opened. thus placing motors 3 and. lin parallel.

The cutout switch U0 is a four-bladed double-throw switch having two effective contacts 39 and 40 when thrown to cut-out 'When this cut-out switch CO is thrown: to its cut-out position it opens the normal position. The four blades of the switch are designated as A1, 42,43 and 44, respectively. The blade 41 forms a part of the connection between contact finger r and the coil of contactor R, this connection being carried in series through the blades 41 and 37.- of the between the contact finger c and the coil of contact finger C; The blade 44 forms a .part of the connection between the contact finger d and the coil of contactor D.

The contact 39 is connected to the conductor leading from the r finger to the coil of con- The contact 40 is cross connected tactor R to the upper fixed contact of the blade 42,

circuit of the coil of contactor R and connects said coil, through the contact 39, with; i the finger 13. It also opens the circuit of the C contactor, but through. vthe'contact 40 connects the coil of B contactor with 0 contact finger. It also opens the circuit of the coil,

of contactor D. It is not believed to be necessary to trace out the sequence of operations withthis cut-out switch thrown since the combinations of motors 1 and 2 efiected thereby are similar to those effected of motors 3 and 4 when motors 1 and 2 are out out. The circuits in the various positions of the master controller ,can be readily traced in Fig. 7.

It will be noted that the arrangement shown is well adapted to train control with a plurality of master controllers located on different cars, since the operation of the cut-out switches in noway affects the train line wires. As shown in Fig. 7, all the circuit connections leading to the coils of the several contactors consist of taps taken off the group of train wires Tiv.

,In Fig. 8 we have shown a modified system which effects the same general motor combinations as that just described, but which differs therefrom mainly in the de tail arrangement of the control circuits, their interlocks, and the arrangement of the cut-out switches. In this form the cut-out switches, are not entirely independent of the power circuits; but the major portion of the operations of these switches is effected in the control circuits. This necessitates some change in the connections of the power circuits, in order to carry some of them through the cut-out switches. The differ ence in this respect between Figs. 6 and 8 will be best understood by a comparison of the two diagrams. It will be noted by such comparison that the main difference is the omission of contactor E. To avoid confucuit-ing of the motors.

sion, the motors, the Various contactors, and the contact fingers of the master controller MU are given the same reference characters as in the preceding figures, and new reference characters are only employed where there is some essential change in the construction or arrangement. In this figure it will be understood that the contactors indicated generally in the power circuits are the same contactors which are shown in detail in the control circuits. This plan has been followed in order to simplify the diagram and enable the figure to be more readily compared with Figs. 6 and 7.

One system of the interlocks shown in Fig. 8 is for the purpose of preventing short cir- It will be seen that if contactors A, D and G should by any reason he closed at the same time there would be a. direct short circuit from trolley to ground. W e therefore provide electrical interlocks which make it impossible for more than two of these three contactors to be closed or remain closed at the same time. That is to say, whereby contactor 'A cannot be closed unless either or both contactors D and G are open; whereby contactor D cannot be closed unless either or both A and G are open; and-whereby contactor G cannot be closed unless either or both A and D contactors are open. follows: The circuit wire leading from con- This is accomplished ,as'

troller finger a, to the coil or contactor A is carried through a set of contacts 45 of the contactor G which are closed only when contactor G is open. Shunt connections 46 of this conductor also lead to contacts 47 of the contact'or D, these contacts being closed only when contactor D is open. Therefore, the coil of contactor A cannot be energized unless either D. or G, or both of them are open.

In alike manner the circuit wire connecting finger cl with the coil of contactor D is carried through a second set of contacts 48 of cont actor G and which areclosed only when said contactor is open. 1 A shunt 50 of said conductor also extends to a set of contacts 51 of contactor A and closed only when contactor A is open, therefore the coil of D cannot normally be energized unless either contactor A or contactor G, or both of them are open. Likewise, the conductor leading from the contact finger g to the coil of contactor G is carried through a set of contacts 52 of the contactor D and which are closed only when contactor D is open; and a shunt conprovide the contactor R with two sets of back contacts 55 and 56 which are closed only when contactor R is closed. One of the fixed contacts of the set of contacts 55 is connected to the conductor leading from the finger r to the coil of contactor R. The other fixed contact of this set is connected to the coil of contactor R One of the fixed contacts of the set of contacts 56 is also connected to the coil of R and the other fixed contact is connected to a conductor 57 which-has a branch leading to a contact point 58 of the cont-actor D and another branch leading to a contact point 59 of the contactor G. Opposite the contact point 58 is a contact (50 which is connected to the coil of contactor D. The two contacts 58 and 60 are arranged to be bridged by the movable contact of the set of contacts 52 when contactorD is closed. Opposite the contact 59 is a contact 61 which is connected to the coil of contactor G. Contacts 59 and 61 are arranged to be connected by the movable contact of the set of contacts 48 when contactor G is closed. By this system of interlocks it will be seen that on the return stroke of the controller drum, R contactor will stay closed as long as r finger is energized. The holding closed of contactor R makes live contacts at 58 and 59, so that when these contactors close they will remain closed so long as r finger engages its corresponding contact on the drum. hen this finger opens on the return stroke (between the first and second positions) they finger has been energized through its segment on the drum. This holds Cr contactorclosed till the off position is reached; and by the current feeding back through the contacts 59 and 61 of the G contactor, contactors D, R and R? will also be held closed until the off position is reached. It will be seen that these holding interlocks do not come into play until after the fourth notch on the forward movement of the controller when the contact finger r engages its contact segment. We therefore provide an additional interlock which will operate to hold the D contactor closed during. the return to off position should the drum be moved backwardly before the interlocks have become effective. This is accomplished by means of the set of contacts 62 on the back of contactor. C and which are closed when contactor C is opened. One of the fixed contacts of this set is connected to the control wire leading from finger a to the coil of contactor A; and the other fixed contact (32 is connected to a contact 63 on the back of contactor D. Contact 63 isplaced opposite a contact 64:, connected to the coil of coma ctor D, and these two contacts are connected by the movable contact 47 when contactor D is closed. In this manner the D contactor will be held closed on the return stroke until off position is rcachc? although the forward movement of the controller drum may not have extended beyond its fourth position. Motors numbers 1 and 2 in this modification are cut out by means of a five-bladed double-throw cut-out switch COS, and motors ninnbers 3 and are arranged to be cut out by a three-bladed double-throw cut-out COS. The cut-out switch COS is connected in two of the power circuits and in three of the control circuits. The middle point of the first blade 65 of this switch is connected to trolley through the resistance Re, while the top contact of this blade is connected to the bcginning of number 1 motor for normal operation. The fixed contact 66 is connected to the end of number 4: motor, so that when the switch is thrown to its cut-out position the number 3 and number i motors may be connected in series to trolley through the resistance Re. The second blade 67 of this switch has its top contact connected witl. the conductor leading .to the end of number 4: motor and its middle point is connected through one of the blades of the switch COS to the power circuit at a point intermediate the contactors D and G.

The conductor leading from contact finger b to the coil of contactor 13 passes, normally, through the third blade 68 of the cut-out switch. The lower fixed contact 69 of this switch is connected through the upper contact of the fourth blade 70 and through the cut-out switch CO tor C. The condov leading from contact finger c to the coil of contactor C is ne mally carried through the fourth blade 70 of this switch. The upper contact of the fifth blade 71 is connected to contact finger r.

The middle point of this fifth blade is connectcd through the cut-out switch COS with the coil of contacts: R. The lower fixed contact 72 is connected through a lower contact 73 of switch COS withcoutact finger 7*. By reason of the cross connection to the contact 69, when the switch COS is thrown to cut-out position, the control wire to the B contactor is cut off and the b finger is connected to the coil of the C contactor. By reason of the lower fixed contact 7 when switch COS is moved to its cut-out p sition, the circuit of the 1" finger is open and the coil of the R contactor is connected to the 1' finger. In this .way the resistance Re is not short circuited by its contactor until the 1' finger is energized, which occurs between the fourth. and fifth positions of the controller. \Vhen this switch is in thrown position, the sequence of operations is as follows: At the first position contactor A closes; G also closes, but its circuit is open at the second blade of'the cut-out switch. At the second position the r finger is energized, but the control wire from this finger is'open. At the with the coil of contaci;

as contactor R thus short circuiting the re- 2 sistance and putting the two motors numbers 3 and 4: in series across-the line to ground; At the sixth position, the b finger energizes contactor C, putting number 4. motor across the line, and short circuiting the number 3 motor. At the seventh position contactor D closes and puts motor number 3 across the line in parallel with motor number 4.

To cut out'the number 3 and number 4 motors, the first blade 74. of the switch COS opens the control wire of the cfinger to thei C contactor. The second blade 7 5 opens the 1 control wire to the r finger and connects the i R contactor to the 7' finger. The third blade 76 opens the power circuit between the number 4: motor and the D and G contactors. The sequence of operations at the different positions of the controller need not be traced ,out in detail as they are similar to those described in connection with the cutting out of the number '1 and number 2 motors. In this form of our invention it will'be seen that there are only four wires of the power circuits carried through the cut-out switches, the other cutting out operations occurring wholly in the control circuits.

In Figs. 9, 10 and 11 we have illustrated another modification. In these figures the operations in passing from the series-parallel to the full-parallelposition are substantially the same as in the previous forms. We have, however, in this form provided means whereby at least three of the motors may be kept actively in circuit at all times in passing from series to series parallel position. The power circuit is, in general, similar to that shown in the preceding figures, except for the fact that the external resistance Re is connected between the fourth motor and ground; and-except that an additional conta'ctor Hiscmployed. The energizing coil of this contactor (not shown) is connected to contact finger h of the master controller MC". This contactor comes into play at the third running position and also in the following transitory position to keep the numher 3 motor connected in series with motors numbers 1 and 2. In the first intermediate transitory position following the third position motor number 4 is connected in parallel with the other three motors in series and it is in series with the resistance Re. In the sec end-transitory position the two motors 3 and L are in parallel with the motors 1 and 2, but

are connected in series with the resistance Re. At-the fifth position this resistance is cut out, leaving the motors 1n series-parallel.

In these figures we have also shown a transitory position intermediate positions 4 and 5 in which the resistance Re is placed in series with the number 3 motor, number 4 motor having been short circuited. The succeeding motor combinations arethe same as in the' In Fig. 12 we have shown, diagrammatipreceding figures.

cally, a circuit and control arrangement for effecting the various motor combinations of Fig. 3 by a simple controller of the drum type, instead of by a master controller and a series of contactors controlled thereby.

In this figure the motor circuits are connected directly to the contact fingers J, K, L, S, M, P, Q, N ,and V, which are adapted to engage the series of contacts carried by the drum. The circuits in the various positions of the drum can be readily traced from this diagram and need not be described in detail.

designates an insulating barrier on the drum interposed between the drum contacts which are connected to the trolley side of the circuits and the contacts which are connected to the ground side of the circuits.

81 is a cut-out, switch having a movable contact member 82 carried by the shaft 83 of the controller drum. This switch is interposed in the circuit between the trolley and the drum, and is arranged, as will be readily seenfrom Fig. 13, to open and close the trolley circuit, respectively, before such circuit is opened or closed by the drum contacts. The circuit from-trolleyto the drum' is preferably carried through a contactor Si to coil 85 which is directlycontrolled by the switch 81.

It will be seen from the foregoing detailed description that our invention accomplishes the objects previously stated, and that it provides a simple and efficient method of control in which thereis a minimum change in speed and load on the motors from one position to another, with a minimum use of resistance, thus permitting a very gradual speed acceleration in passing from series to the parallel positions. The number of contacts necessary to effect the various motor combinations is reduced to a minimum; destructive arcing at the contacts is prevented; the possibility ofa direct short circuit around the motors is obviated, and the cutting out of either pair of motors is effected with a minimum disturbance of the power circuits. 4 y

We desire'it understood that we do not limit ourselves to the particular form of contactors which have been shown and described, inasmuch as we may employ any suitable form of those devices capable of be ing' controlled by a master controller; also that the construction and arrangement of the cut out switches, as well as the type of such. switches employed, may be changed, and that minor changes may be made in the general system of motor combinations etiected, all within the scope of our broader claims In the foregoing description we have merely described the arrangement of the motors and their connections for a single car, but it will readily be understood by those familiar with the art that the same system could be used on a series of cars controlled by a master controller.

I'Vhat we claim is:

1. In the control of sets of four electric motors, the steps which consist in starting with all the motors in series, subsequently connecting them in series-parallel groups, and then connecting the motors all in parallel by successively establishing as many different parallel current paths as there are motors, and while establishing such parallel paths, maintaining at least three of: the motors actively in circuit; substantially as descr bed;

In the control of four electric motors, the method of changing the motors from series-parallel relation to full-parallel relation, which consists in successively establishing as many different parallel current paths as there are motors, and while establishing such parallel paths maintaining at least three of the motors actively in circuit; substantially described.

3. In the control of four electric motors, the method of changing the motors from series-parallelrelation to full-parallel relation, which consists in successively connecting the motors one after another to receive the full line voltage, and maintaining at least three of the motors actively in circuit while so connecting them; substantially as described.

s. In the control of four electric motors, the method -,'of changing the meters from series-parallel to full-parallel which consists in first cutting out one of the motors and leaving two-30f them in'series and the third in parallel with the two which are in series, then reconnecting said motor in parallel with the motors so left, then cutting out one of the two motors in series and finally connerting the last named motor in parallel with the others; substantially as described.

5. In the control of four electric motors, the method of changing the motors from series-parallel to full parallel, which con sists in cutting out one of the motors, leaving.

two of them in series and the third in parallel with the two in series, and connecting in resistance with said third motor, then re moving said resistance and re-connecting the cut out motor in parallel with the motors so left, then cutting out one of the two motors which are in series and reconnecting it in parallel with the other motors; substantially described.

6. In the control of four electric motors, the method of changing the motors from series to parallel, which consists in first connecting them in series-parallel groups and maintaining at least three of the motors actively in circuit at all times, while so connerting them, then connecting the motors all in parallel, and maintaining at least three of the motors acti 'ely' in circuit while making this connection; substantially as de scribed.

7. In the control of four electric motors, the method of changing the motors "from series to series-parallel which consists in first cutting out one of the motors and reconnecting it in series with external resistance and in parallel with the other three motors, and thenconnecting one of the other three motors into the circuit in place of the resistance; substantially as described.

8. In the control of four electric motors, the method of changing, the motors from series to parallel, which consists in first connecting them in series-parallel groups and finally connecting them all in parallel, while maintaining at least three-of the motors actively in circuit at alltimes, and inserting external resistances of different values in the circuit at different times while effecting these changes; substantially as described.

9. In the control of electric motors, the method which consists in holding certain of the power circuits closed during the reverse movement of the controller to its ofi' circuit position, and thereby maintain the motors in a closed local circuit while opening the power connections thereto; substantially as described. i

10. In the control of electric motors, the method of preventing arcing at the control contacts, which consists in holding certain of the power circuits closed after they would be normally opened during the return movement or the controller; substantially as described. I

11. In the control of four electric motors, the method of'changing the meters from series to parallel, which consists-in first connecting them in series-parallel groups and maintaining at least three of the motors aetivcly in circuit at all times while so con necting-them, then successively connecting the motors to receive the full line voltage, and maintaining at least three of the motors actively in circuit while makin these connections; substantially as descri ed.

12. In the control of four electric motors, the method of changing the motors from series to parallel, which consists in first cutting out one of the motors and re-connecting it in series with external resistance and parallel with the other three motors, then conthe method of changing the motors from.

series to parallel, which consists in first connecting them in series-parallel groups and finally connecting them all in parallel by successively connecting them one after an other acrossthe line, and maintaining at least three of the motors actively in circuit at all times, external resistances of different values being inserted in the circuit at different times While effecting these changes; substantially as described.

14. Apparatus for the control of electric motors, comprising contacts and circuit connections for first connecting all the motors inseries, then connecting them in seriesparallel, and finally allin ptilallel, said contacts and connections being arranged to maintain at least three of the motors actively in circuit while establishing such changes; substantially as described.

15. Apparatus for the control of electric motors, comprising contacts and circuit connections for first connecting all the motors in series, then connecting them in series-parallel, and finally all in parallel, said contacts and connections being an ranged to maintain at least three of the motors actively in circuit While establishing the change from series to series-parallel; substantially as described.

16. Apparatus for the control of electric motors, comprising contacts and circuit connections for first connecting all the motors in series, then connecting them in seriesparallel, and finally all in parallel, said contacts and connections being arranged to maintain at least three of the motors actively in circuit while establishing the change from series-parallel to parallel; sub stantially as described.

17.'Apparatus for the control of electric motors, having contacts and circuit connections for shifting the motors from seriesparallel relation to full-parallel relation, said contacts and connections acting to suecessively connect the motors one after another across the line, and to retain at least three of the motors actively in circuit while so connecting them; substantially as .described.

18. Apparatus for the control of electric motors, comprising a plurality of contactors for controlling the power circuits, a master controller for controlling the operation of the contactors, and said master controller and contact'ors having means whereby certain of the contactors are held closed during the return stroke of the master controller to the off position after the circuits of such contactors are normally opened by the master controller; substantially as described.

19. Apparatus for the control of electric motors, comprising a plurality of contactors for controlling the power circuits of the motors, a master controller having contacts and circuit connections for. controlling the operation of the contactors,- said contactors having means whereby certain of them can only be closed when certain other contactors are open, and the controller and contactors also having means whereby certain of the contactors remain closed during the return movement of the master controller beyond the times at which their circuits would normally be opened by the master controller; substantially as described.

20. Apparatus for the control 0t electric motors, comprising a plurality of contactors for controlling the power circuits of the motors, a master controller for controlling the operation of the contactors, certain o'l said contactors ha ing inter-connected circuits whereby they are maintained closed during the return stroke of the master controller'beyond the times at which their normal circuits are opened by the master controller; substantially as described.

21. Apparatus for the ,control of electric motors, comprising a series oi contactors for controlling the power circuits, a master controller and control circuits leading therefrom. for controlling the operation of the contactors, and motor cut-out switches having at least a major portion of their circuit changing contacts located in the control circuits only; substantially as described.

22. In apparatus for the control of electric motors, a series of contactors for controlling the power circuits of the motors. a master controller and control circuits leading therefrom for controlling the operation of the said contactors, and motor cut-out switches,

said cut-out switches being located entirely in the control circuits; substantially as do scribed.

In testimony whereof, we have hereunto set our hands.

PEAR-ll N. .TONllS. JAB H63 A. WELSH.

.Vitnesses:

.Tnssr. B. llnimun,

H. M. ConwiN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. 0.? 

